Peptide Delivery Technologies: Beyond the Needle
Injectable peptides face real barriers — needle phobia, cold storage, poor compliance. Here's where the science stands on oral, transdermal, microneedle, nasal, inhaled, implantable, and nanoparticle delivery systems.
Peptide Delivery Technologies: Beyond the Needle
Peptides work. That much is settled. GLP-1 receptor agonists like semaglutide have reshaped how we treat type 2 diabetes and obesity. GnRH analogs manage prostate cancer. Growth hormone-releasing peptides address pituitary deficiencies. The pharmacology is solid.
The delivery, however, is a different story.
Most therapeutic peptides still require injection — subcutaneous, intramuscular, or intravenous. And that single requirement creates a cascade of real-world problems: patients who avoid treatment because they fear needles, medication that degrades without refrigeration, and adherence rates that drop off a cliff once people go home with a box of syringes.
The gap between what peptides can do in a clinical trial and what they actually do in everyday life is largely a delivery problem. This article maps every major technology working to close that gap.
The Case Against the Needle
Needle Phobia Is More Common Than You Think
Injection phobia affects between 7% and 22% of the general population, according to prevalence studies. That is not a small fringe group. Among people with chronic conditions requiring self-injection, the numbers get worse: roughly 35% of newly diagnosed diabetic patients prescribed subcutaneous insulin delayed starting therapy specifically because of needle fear, according to survey data. In a study of 500 type 2 diabetes patients on injectable antidiabetic therapies, 37% reported feeling afraid when thinking about a needle.
This is not squeamishness. It is a documented clinical barrier. Needle fear does not usually resolve on its own, and downstream, it increases illness risk through decreased adherence to care across the lifespan. When 67% of endocrinologists report that injection fear is a major concern for patients initiating injectable treatment, the problem has moved from the psychology literature into the clinic.
Compliance Collapses Outside the Trial
Clinical trials produce impressive numbers for injectable peptides because participants receive ongoing monitoring, coaching, and support. Real-world adherence tells a different story. Fewer than 50% of chronic diabetic patients adhere to their injectable insulin dosing regimen. For GLP-1 receptor agonists administered by injection, one-year persistence rates frequently fall below 60%.
Intarcia Therapeutics quantified this gap directly: poor adherence with pills and injections in type 2 diabetes accounts for a 75% reduction in efficacy between real-world patients and clinical trial participants. That is a staggering loss — three-quarters of a drug's potential benefit evaporating because people don't take it as prescribed.
Cold Chain Costs and Complexity
Most peptide therapeutics require refrigerated storage at 2-8 degrees Celsius. The global cold chain market for pharmaceuticals was valued at $6.4 billion in 2024, and more than 85% of biologics require temperature-controlled manufacturing, storage, and distribution. Every link in that chain — from manufacturing floor to pharmacy shelf to patient's refrigerator — represents a point where temperature excursions can degrade the product.
The logistics are brutal. A 2012 U.S. government audit found that 76% of vaccine providers reviewed had exposed products to inappropriate temperatures for at least five cumulative hours over a two-week period. Peptides shipped through multiple transport modes — air, ground, sea — face temperature variability at every transfer point. For patients in tropical climates or rural areas without reliable refrigeration, maintaining peptide stability is not just inconvenient; it can be impossible.
These three problems — needle phobia, poor compliance, and cold chain fragility — define the design brief for every alternative delivery technology described below.
Oral Delivery: The Holy Grail Gets Closer
For decades, oral peptide delivery was considered impossible. The gastrointestinal tract presented an obstacle course: stomach acid denaturing peptide structures, proteolytic enzymes chopping them apart, a thick mucus layer blocking diffusion, and an epithelial barrier that large hydrophilic molecules simply could not cross. Oral bioavailability for most unmodified peptides was effectively zero.
That changed with semaglutide.
The SNAC Breakthrough
Rybelsus (oral semaglutide), approved by the FDA in 2019 for type 2 diabetes, co-formulates the peptide with 300 mg of SNAC — sodium N-(8-[2-hydroxybenzoyl] amino) caprylate. SNAC is a transcellular permeation enhancer that works through three complementary mechanisms:
- Local pH buffering — SNAC raises the pH around the dissolving tablet to approximately 5 or above, inactivating pepsin and protecting the peptide from enzymatic destruction.
- Monomer promotion — SNAC changes the polarity of the local solution, weakening the hydrophobic interactions that cause semaglutide to clump into oligomers. Only the monomeric form has enough diffusional mobility to cross cell membranes.
- Membrane fluidization — SNAC increases the fluidity of gastric epithelial cell membranes, allowing semaglutide to pass through the cells themselves (transcellular absorption) rather than between them.
Scintigraphic imaging in human volunteers confirmed that absorption happens in the stomach, not the intestine. The oral bioavailability is low — roughly 0.8% — which means the tablet contains far more peptide than actually reaches systemic circulation. But that 0.8% is enough. The 14 mg oral dose produces plasma levels that reduce HbA1c by comparable amounts to injected semaglutide.
In late 2025, the FDA approved a 25 mg oral semaglutide tablet (Wegovy) for chronic weight management, with the OASIS 4 trial showing 13.6% mean weight loss at 64 weeks. This oral formulation represented a landmark: the first oral GLP-1 for weight loss.
Beyond Semaglutide: The Oral Pipeline
The oral peptide space is now crowded. Eli Lilly's orforglipron, a non-peptide oral GLP-1 receptor agonist, completed Phase 3 trials with results showing HbA1c reductions of 1.3-1.6% and average weight loss of 7.9% over 40 weeks in the ACHIEVE-1 study. Unlike semaglutide, orforglipron can be taken without food or water restrictions because it is a small molecule rather than a peptide — sidestepping the absorption challenge entirely.
MYCAPSSA (octreotide) uses a different enhancer technology — Transient Permeation Enhancer (TPE) — to deliver the somatostatin analog orally for acromegaly. Despite even lower bioavailability (~0.7%), clinical trials showed efficacy, and for many patients the twice-daily pill is preferable to monthly depot injections.
Device-based approaches are also advancing. Rani Therapeutics developed the RaniPill, a robotic capsule containing sugar-based microneedles that deploy when an osmotic mechanism inflates a small balloon inside the intestine, injecting the peptide directly into the intestinal wall. MIT's SOMA (Self-Orienting Millimeter-Scale Applicator) and LUMI devices use similar ingestible injection concepts.
Pinnacle Medicines closed an oversubscribed $89 million Series B round in March 2026 to advance AI-designed oral peptide therapeutics through clinical proof of concept, focused on immunology and cardiometabolic disease. The money flowing into this space reflects confidence that oral peptide drugs are moving from exception to norm.
Oral Delivery: The Trade-offs
| Advantage | Limitation |
|---|---|
| Familiar pill format, high patient preference | Very low bioavailability (typically <1%) |
| No needles, no injection training | Higher doses required, increasing manufacturing cost |
| Room temperature storage possible for some formulations | Food timing restrictions (fasting required for oral semaglutide) |
| Scalable manufacturing | GI side effects (nausea) remain common |
Transdermal and Microneedle Patches
Traditional transdermal patches (the kind used for nicotine or fentanyl) work well for small, lipophilic molecules that can passively diffuse through the skin. Peptides are neither small nor lipophilic. The stratum corneum — the outermost skin layer — acts as an impenetrable barrier to hydrophilic macromolecules.
Microneedle patches solve this by physically breaching the barrier with arrays of microscopic needles, typically 200-800 micrometers long — long enough to reach the dermis but short enough to avoid pain receptors and blood vessels. The result is drug delivery through the skin without the sensation of an injection.
Types of Microneedles
- Dissolving microneedles — Made from water-soluble or biodegradable polymers (hyaluronic acid, polyvinylpyrrolidone, PLGA) with the drug embedded in the needle matrix. The needles dissolve in the skin within minutes, releasing their payload. No sharps waste.
- Coated microneedles — Solid needles (often titanium) coated with a drug formulation. The coating dissolves upon skin insertion. Zosano Pharma's ZP-Glucagon patch uses this approach with a 3 cm squared array of coated titanium microneedles.
- Hollow microneedles — Miniature hypodermic needles that allow liquid drug formulations to flow through them. More complex to manufacture but can deliver larger volumes.
- Hydrogel-forming microneedles — Swell upon insertion to absorb interstitial fluid, creating a continuous delivery channel. Can provide sustained release over hours.
Where the Clinical Data Stands
In a Phase 2 trial of Zosano's ZP-Glucagon patch, both the 0.5 mg and 1.0 mg patch doses normalized blood glucose in 100% of subjects with type 1 diabetes experiencing insulin-induced hypoglycemia. Onset of action was comparable to intramuscular injection, and no safety issues emerged. The trial enrolled only 16 participants in a crossover design, so larger studies are needed.
Daewoong Pharmaceutical initiated Phase 1 clinical trials for a semaglutide microneedle patch using its proprietary CLOPAM (Closed-Packed Aeropressured Microneedle) platform, secured by six international and 23 domestic patents. The company reported over 80% bioavailability for semaglutide in human pilot studies — a dramatic improvement over the sub-1% oral bioavailability — and aims for commercialization by 2028.
A Lancet-published Phase 1/2 trial (2024) in The Gambia tested a measles and rubella vaccine microneedle patch in 45 adults, 120 toddlers, and 120 infants. Among infants, 93% seroconverted to measles and 100% to rubella — essentially matching subcutaneous injection rates. The patch was applied to the wrist for five minutes and removed. No safety concerns emerged.
Patient acceptability studies consistently show 70-90% of participants preferring microneedle patches to intramuscular injection with conventional needles — a preference strong enough to meaningfully improve adherence for chronic therapies.
Programmable Release: One Patch, One Month
Perhaps the most intriguing advance is programmable scheduled release microneedles (PSR-MNs). Researchers have demonstrated a 2 cm x 2 cm patch containing four core-shell microneedle arrays that release semaglutide in programmed pulses every seven days, sustaining drug efficacy for a full month from a single application. If this translates to human use, it could replace four weekly injections with one painless patch.
Nasal Delivery: Fast Absorption, Size Limits
The nasal mucosa offers a large, highly vascularized surface area, avoids first-pass liver metabolism, and provides a direct pathway to the central nervous system via olfactory and trigeminal nerve routes. Several peptide drugs already use this route: desmopressin (DDAVP nasal spray for diabetes insipidus), calcitonin (Miacalcin nasal spray for osteoporosis), and oxytocin (for research applications).
Intranasal peptide delivery works best for peptides under 1,000 daltons. Davunetide (825 Da) achieved approximately 100% nasal bioavailability in studies. But bioavailability drops sharply above 1,000 Da: oxytocin (1,007 Da) achieves roughly 12% bioavailability via nasal spray compared to intramuscular injection, and desmopressin nasal spray (Stimate) ranges from 3.3% to 4.1%.
Three barriers limit nasal peptide absorption: mucociliary clearance (the nose's self-cleaning mechanism removes drug before it can be absorbed), enzymatic degradation in the nasal mucosa, and the low permeability of the nasal epithelium to larger molecules.
Strategies to Improve Nasal Bioavailability
Researchers are working around these limitations with absorption enhancers like chitosan (a mucoadhesive biopolymer that temporarily opens tight junctions), cell-penetrating peptides that shuttle cargo across cell membranes, and nasal dry powder formulations that resist mucociliary clearance better than liquid sprays. Combining two or three of these strategies can push bioavailability significantly higher.
The nose-to-brain pathway is generating particular interest for neurological peptides. Intranasal delivery of insulin, BDNF, and neuropeptide Y can bypass the blood-brain barrier, reaching the CNS at therapeutic concentrations without systemic exposure. This makes nasal delivery uniquely suited for peptide therapies targeting Alzheimer's disease, Parkinson's disease, and other CNS conditions.
Nasal Delivery: The Trade-offs
| Advantage | Limitation |
|---|---|
| Rapid onset (minutes) | Poor bioavailability for peptides >1,000 Da |
| Non-invasive, self-administered | Mucociliary clearance limits absorption window |
| Direct nose-to-brain pathway for CNS peptides | Variable dosing (affected by congestion, breathing technique) |
| Established regulatory pathway (multiple approved products) | Limited to low-dose peptides |
Inhaled (Pulmonary) Delivery
The lungs offer a remarkably efficient absorption surface: 75-100 square meters of alveolar-capillary area, thin epithelial barriers, and low metabolic activity that protects peptides from degradation. These features make pulmonary delivery attractive for peptides, particularly insulin.
Afrezza: The Cautionary Success Story
Afrezza (Technosphere Insulin), approved by the FDA in 2014, delivers recombinant human insulin adsorbed onto fumaryl diketopiperazine (FDKP) microparticles via a pocket-sized inhaler. It reaches peak plasma concentration in 12-15 minutes — faster than any injectable rapid-acting insulin — with a shorter duration of action (2.5-3 hours vs. 3-4 hours for insulin analogs).
Clinical trials enrolled 3,017 subjects and showed 20-65% less hypoglycemia compared to active comparators regardless of HbA1c level. That speed advantage matters: inhaled insulin more closely mimics the body's natural first-phase insulin response after eating.
But Afrezza also illustrates the challenges of pulmonary peptide delivery. Lung function declines slightly (about 40 mL FEV1 reduction over two years in trials), requiring spirometry monitoring before and during treatment. Two lung cancer cases occurred in Afrezza-treated patients (both with histories of heavy tobacco use), creating a safety overhang. And the product is contraindicated in patients with chronic lung disease — asthma and COPD.
Despite these limitations, Afrezza remains on the market and represents proof-of-concept that the lungs can deliver therapeutic peptide doses. Research into inhaled peptide therapies for applications beyond insulin — including antimicrobial peptides, pulmonary hypertension treatments, and local lung therapies — continues to advance.
Implantable Devices: Set It and Forget It
For patients with chronic conditions requiring years of continuous therapy, the question shifts from "how do we make each dose easier?" to "can we eliminate dosing altogether?" Implantable peptide devices answer that question.
FDA-Approved Implants Already Exist
The concept is not theoretical. Several peptide implants are already in clinical use:
Histrelin implants (Supprelin LA) — A 50 mg histrelin acetate subcutaneous implant that delivers approximately 65 micrograms per day of this GnRH agonist peptide for 12 months. Approved by the FDA in 2007 for central precocious puberty, it is inserted in the inner upper arm during a brief procedure. In Phase 3 trials, 31 of 32 eligible patients continued annual re-implantation, and mean peak stimulated LH levels remained suppressed throughout treatment. Bioavailability from the implant is 92%.
Leuprolide depot formulations (Lupron Depot, Eligard) — While technically injectable depots rather than implants, these use biodegradable PLGA/PLA polymer microspheres or in-situ-forming gels to release the GnRH analog leuprolide continuously for one to six months from a single injection. The Lupron Depot microsphere formulation and the Eligard in-situ-forming implant represent two different engineering solutions to the same problem: converting a peptide that would otherwise require daily injection into a quarterly or semi-annual treatment. More than 20 PLGA-based products have been approved by the FDA since 1986.
ITCA 650: The Osmotic Mini-Pump
Intarcia Therapeutics' ITCA 650 is the most ambitious implantable peptide device to reach late-stage clinical trials. A matchstick-sized osmotic mini-pump placed subdermally, it continuously releases exenatide (a GLP-1 receptor agonist) in zero-order kinetics — a flat, constant release rate — for three to twelve months.
The FREEDOM clinical trial program produced striking results:
- FREEDOM-1 (n=460): HbA1c reductions of 1.1% and 1.2% for the 40 and 60 mcg/day doses versus 0.1% for placebo. Weight loss of 2.3-3.0 kg versus 1.0 kg. Patients not on sulfonylureas saw an average 1.7% A1C decline.
- FREEDOM-2 (n=535): Head-to-head against sitagliptin (Januvia), ITCA 650 delivered nearly double the A1C reduction (-1.5% vs. -0.8%) and triple the weight loss (-4.0 kg vs. -1.3 kg) over 52 weeks.
- FREEDOM-1 HBL: In patients with very high baseline A1C (10-12%), the open-label study showed a mean 3.4% A1C reduction from a baseline of 10.8%.
Despite these results, the FDA issued a Complete Response Letter citing manufacturing concerns, and the device was placed on clinical hold. Intarcia resubmitted its NDA, and the FDA accepted it for review. The regulatory path forward remains uncertain, but the clinical data demonstrated that continuous subcutaneous peptide delivery via implant can match or exceed the efficacy of the best oral comparators — with zero patient adherence required.
Next-Generation Implantable Systems
Research published in Science Advances evaluated a novel implantable system called SUSTAIN for semaglutide delivery. While subcutaneously injected semaglutide was absorbed from the injection site over 120 hours, the SUSTAIN hydrogel device retained and released the drug over 264 hours — more than doubling the delivery window.
Biodegradable polymer technology is evolving rapidly. PLGA-PEG-PLGA thermosensitive hydrogels can be injected as liquids that solidify at body temperature, forming depots without surgical implantation. These gels can deliver both hydrophobic and hydrophilic drugs, biodegrade harmlessly, and stabilize peptide payloads for weeks. A 2026 study in Frontiers in Materials demonstrated such a hydrogel serving as a sustained-release depot for mesenchymal stem cell-derived exosomes, promoting wound healing through controlled release.
Liposomal and Nanoparticle Systems
Nanoparticle-based delivery represents a broad category of technologies that encapsulate peptides within engineered particles — typically 10 to 1,000 nanometers in diameter — to protect them from degradation, control their release, and direct them to specific tissues.
The Major Platforms
Liposomes are spherical vesicles made from phospholipid bilayers enclosing an aqueous core. They have been used in drug delivery since the 1990s and remain one of the most clinically validated nanocarrier platforms, with 68 approved formulations as of 2025. Liposomes can encapsulate both hydrophilic peptides (in the aqueous core) and hydrophobic ones (in the lipid bilayer).
Lipid nanoparticles (LNPs) gained global recognition through the COVID-19 mRNA vaccines. The same technology can deliver peptide therapeutics. In 2024, more than 42 new clinical trials employed LNP carriers across 18 different indications, from solid tumors to metabolic disorders. The market for liposomal and LNP drug delivery systems is projected to reach $15.8 billion by 2034.
Polymer nanoparticles (PLGA, chitosan, polyethylene glycol) offer tunable degradation rates, allowing programmable release profiles. PLGA nanoparticles loaded with liraglutide, for example, can sustain release for up to 15 days in a biphasic profile — eliminating the need for daily subcutaneous injection.
Peptide-Functionalized Nanoparticles
An interesting twist: peptides are not just passengers in nanoparticle systems — they can also be the targeting mechanism. Tumor-homing peptides attached to nanoparticle surfaces can direct drug-loaded particles specifically to cancer cells, exploiting molecular differences between healthy and malignant tissue. Research from the University of Pennsylvania demonstrated that LNPs functionalized with brain-targeting peptide RVG29 significantly improved neuronal transfection after systemic administration, suggesting a path toward treating neurological conditions with nanoparticle-delivered therapies.
The Translational Gap
Despite enormous preclinical activity, a significant gap remains between laboratory and clinic. Of the thousands of published nanomedicines and preclinical candidates, only an estimated 50-80 have achieved global regulatory approval by 2025. Manufacturing consistency, scale-up challenges, and demonstrating clinically meaningful advantages over simpler formulations remain hurdles. But the $1.05 billion in platform acquisitions completed in 2024 alone suggests the pharmaceutical industry believes the gap will close.
Comparison: All Delivery Technologies at a Glance
| Technology | Bioavailability | Duration | Clinical Stage | Key Advantage | Key Limitation |
|---|---|---|---|---|---|
| Subcutaneous injection (current standard) | 70-100% | Hours to days (depot: weeks-months) | Approved, widely used | High bioavailability, established | Needle phobia, cold chain, compliance |
| Oral (SNAC/enhancers) | ~0.8% | Hours | FDA-approved (semaglutide) | Patient-preferred pill format | Very low bioavailability, fasting required |
| Oral (small molecule GLP-1) | ~25-50% (estimated) | Hours | Phase 3 (orforglipron) | No food restrictions, high bioavailability | Not a true peptide (mimetic) |
| Microneedle patches | Up to 80%+ | Minutes to 1 month (programmable) | Phase 1 (GLP-1 patches) | Painless, room-temp stable, high bioavailability | Manufacturing scale-up, regulatory pathway |
| Nasal spray | 3-100% (size-dependent) | Minutes to hours | Approved (desmopressin, calcitonin) | Rapid onset, non-invasive, CNS access | Poor for large peptides, variable dosing |
| Inhaled | ~10-50% | 2-3 hours | Approved (Afrezza insulin) | Ultra-rapid onset, large absorption area | Pulmonary function concerns, not for lung disease |
| Implantable (osmotic pump) | ~100% (continuous) | 3-12 months | Phase 3 (ITCA 650) | Zero adherence burden, constant levels | Surgical placement, manufacturing complexity |
| Implantable (polymer depot) | 80-100% | 1-6 months | Approved (leuprolide, histrelin) | Long duration, biodegradable | Initial burst release, injection site reactions |
| Liposomal/nanoparticle | Variable | Hours to weeks | Approved (non-peptide); preclinical-Phase 1 (peptide-specific) | Targeted delivery, protection from degradation | Translational gap from lab to clinic |
What Is Closest to Market?
The honest answer depends on what you mean by "market."
Already here: Oral semaglutide (Rybelsus/Wegovy oral), nasal desmopressin and calcitonin, inhaled insulin (Afrezza), and polymer depot formulations for leuprolide and histrelin are FDA-approved and commercially available. These prove that non-injectable peptide delivery works at scale.
Nearest-term pipeline: Eli Lilly's orforglipron filed for regulatory approval in late 2025-2026 and could reshape the oral GLP-1 market. Daewoong's semaglutide microneedle patch targets 2028 commercialization. Intarcia's ITCA 650 osmotic pump has a resubmitted NDA under FDA review.
Medium-term (3-5 years): Programmable microneedle patches, next-generation implantable hydrogel systems, and nanoparticle-peptide conjugates are progressing through preclinical and early clinical work. The convergence of AI-driven peptide design, advanced polymer chemistry, and microfabrication technology is accelerating the timeline.
Long-term (5-10+ years): Closed-loop smart delivery systems — glucose-responsive insulin patches, implantable devices that adjust dosing based on biomarker feedback — remain largely in the animal study phase but represent the ultimate destination: peptide therapy that adapts to the patient's physiology in real time.
The Bottom Line
The injectable peptide era is not ending. For many applications — acute care, high-dose therapies, proteins too large for alternative routes — subcutaneous and intramuscular injection will remain the standard. What is ending is the assumption that injection is the only option.
Every delivery technology described here involves trade-offs. Oral delivery sacrifices bioavailability for convenience. Microneedle patches offer impressive bioavailability but face manufacturing scale-up challenges. Implants eliminate adherence but require procedures. Nasal delivery is fast but limited to small peptides. Nanoparticles promise targeted therapy but struggle to translate from bench to bedside.
The field is moving fast. In 2019, oral semaglutide was considered remarkable. By 2026, it is the baseline that every new delivery technology is measured against. The question has shifted from "can peptides be delivered without needles?" to "which needle-free approach works best for which peptide, condition, and patient?"
For researchers, clinicians, and patients tracking this space, the next five years will be defined by clinical trial readouts from microneedle patches, regulatory decisions on implantable devices, and the arrival of oral GLP-1 competitors that could make the syringe optional for millions of people currently reconstituting peptides at home.
The needle is not dead. But it is no longer the only game in town.
This article is part of PeptideJournal.org's Peptide Delivery Technologies cluster. For deeper coverage of specific technologies, see our articles on microneedle patches, implantable devices, oral peptide formulations, inhaled peptide therapies, and liposomal/nanoparticle delivery.
References and Further Reading
- Buckley ST, et al. "Transcellular stomach absorption of a derivatized glucagon-like peptide-1 receptor agonist." Science Translational Medicine, 2018.
- Henry RR, et al. "Efficacy and Safety of ITCA 650, a Novel Drug-Device GLP-1 Receptor Agonist, in Type 2 Diabetes Uncontrolled With Oral Antidiabetes Drugs: The FREEDOM-1 Trial." Diabetes Care, 2018.
- Rosenstock J, et al. "ITCA 650, a Novel Drug-Device GLP-1 Receptor Agonist, Versus Sitagliptin for Type 2 Diabetes: FREEDOM-2 Trial." Diabetes, 2017.
- Clarke E, et al. "A measles and rubella vaccine microneedle patch in The Gambia: a phase 1/2 trial." The Lancet, 2024.
- Arya J, et al. "Microneedle patches for vaccination in developing countries." Journal of Controlled Release, 2016.
- Klonoff DC. "Afrezza Inhaled Insulin: The Fastest-Acting FDA-Approved Insulin on the Market." Journal of Diabetes Science and Technology, 2014.
- Twarog C, et al. "A new era for oral peptides: SNAC and the development of oral semaglutide." Drug Discovery Today, 2022.
- Lin Y, et al. "PLGA-based implants for sustained delivery of peptides/proteins: Current status, challenges and perspectives." Chinese Chemical Letters, 2023.